1. Field of the Invention
The present invention generally relates to surgical stapling instruments and, more particularly, to surgical staplers having an end effector closing system and a firing system for deploying staples.
2. Description of the Related Art
As known in the art, surgical staplers are often used to deploy staples into soft tissue to reduce or eliminate bleeding from the soft tissue, especially as the tissue is being transected, for example. Surgical staplers, such as an endocutter, for example, often comprise an end effector which is configured to secure the soft tissue between first and second jaw members. The first jaw member often includes a staple cartridge which is configured to removably store staples therein and the second jaw member often includes an anvil. In use, the staples are typically deployed from the staple cartridge by a driver which traverses a channel in the staple cartridge and causes the staples to be deformed against the anvil and secure layers of the soft tissue together. Often, as known in the art, the staples are deployed in several staple lines, or rows, in order to more reliably secure the layers of tissue together. The end effector may also include a cutting member, such as a knife, for example, which is advanced between two rows of the staples to resect the soft tissue after the layers of the soft tissue have been stapled together.
After the driver and the cutting member have been advanced within the end effector, it is often necessary to retract the driver and/or cutting member to their starting positions. Previous surgical staplers have included a return spring which retracts the cutting member relative to the staple cartridge after a release button or toggle switch on the surgical stapler has been actuated by the surgeon. Such staplers, however, are unable to partially retract the cutting member and, as a result, the cutting member must be fully retracted before it can be readvanced. Other previous surgical staplers have included a plurality of triggers which are operatively engaged with systems for closing a jaw member and for advancing and/or retracting the driver and cutting member. Such devices, while suitable for their intended purposes, often require a surgeon to release a trigger operably engaged with the closing system and reposition their hand to grasp a different trigger which is operatively engaged with a system for advancing the staple driver and cutting member. While previous surgical staplers have been developed which have a single trigger for both closing the jaw member and advancing the driver and cutting member, such devices perform both functions upon the initial actuation of the trigger. While suitable in some circumstances, devices which perform both functions in the same trigger actuation are often exceedingly difficult to operate owing to the high degree of force required to actuate the trigger. Furthermore, such devices, as they close the jaw member and deploy staples in the same trigger actuation, do not afford the surgeon with an opportunity to evaluate the position of the closed jaw member and reposition the jaw member before the staples are deployed into the soft tissue. What is needed is an improvement over the foregoing.